It will connect to a station, play for five or six seconds and then rebuffer. This goes on until I turn it off in disgust. Is there anything I can do to make this better?
The device in question is connected to my PC via an Ethernet cable. I'm using a Linksys WRT54G router.

Rebuffering is a classic symptom of network bandwidth restriction or contention. With broadband you buy , say , 2 mbit/s line and the contention ratio could be say 30:1. This means that during peak periods your download speed could be as low is 2 mbits/s divided by 30! High contention ratio (typical with home broadband) and busy times can cause re-buffering. Also some stations have very low performance internet connections. Some countries/locations have problem broadcasting >64kbps or >128kbps/s internet radio broadcast.

Check your router's firmware version...upgrade if you can. If latest, you may even need to downgrade...it's been known to happen! Channel changes (1 or 11), and firewalls may also affect radio streaming, so don't give up on the SB just yet, it might not be the culprit. G'Luck!